Hack together -Wlifetime-extension. Not ready for prime time.

Still gives false positives on any use of a `std::initializer_list` variable (because it extends the lifetime of its backing array). No attempt to update the unit tests.
Quuxplusone · Mar 4, 2020 · 99ca9fc · 99ca9fc
1 parent 1044ee8
commit 99ca9fc
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diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -234,6 +234,8 @@ def FormatZeroLength : DiagGroup<"format-zero-length">;
 
 def InvalidIOSDeploymentTarget : DiagGroup<"invalid-ios-deployment-target">;
 
+def LifetimeExtension : DiagGroup<"lifetime-extension">;
+
 def CXX17CompatMangling : DiagGroup<"c++17-compat-mangling">;
 def : DiagGroup<"c++1z-compat-mangling", [CXX17CompatMangling]>;
 // Name of this warning in GCC.

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -10613,4 +10613,8 @@ def warn_sycl_kernel_return_type : Warning<
   "function template with 'sycl_kernel' attribute must have a 'void' return type">,
   InGroup<IgnoredAttributes>;
 
+def warn_lifetime_extension: Warning<
+  "binding temporary of type %0 to a reference relies on lifetime extension">,
+  InGroup<LifetimeExtension>;
+
 } // end of sema component.
diff --git a/clang/lib/Sema/SemaAttr.cpp b/clang/lib/Sema/SemaAttr.cpp
@@ -97,6 +97,9 @@ static void addGslOwnerPointerAttributeIfNotExisting(ASTContext &Context,
 
 void Sema::inferGslPointerAttribute(NamedDecl *ND,
                                     CXXRecordDecl *UnderlyingRecord) {
+  return;
+  // don't do any of this
+
   if (!UnderlyingRecord)
     return;
 

diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
@@ -7356,6 +7356,13 @@ void Sema::checkInitializerLifetime(const InitializedEntity &Entity,
 
     auto *MTE = dyn_cast<MaterializeTemporaryExpr>(L);
 
+    if (LK == LK_Extended && MTE != nullptr) {
+      VarDecl *VD = dyn_cast<VarDecl>(ExtendingEntity->getDecl());
+      if (!(VD && VD->getNameAsString().substr(0,7) == "__range")) {
+        this->Diag(MTE->getSourceRange().getBegin(), diag::warn_lifetime_extension) << L->getType() << MTE->getSourceRange();
+      }
+    }
+
     bool IsGslPtrInitWithGslTempOwner = false;
     bool IsLocalGslOwner = false;
     if (pathOnlyInitializesGslPointer(Path)) {